In elevator systems with a plurality of elevator shafts cars can often switch between these elevator shafts and move in a plurality of elevator shafts. A high transportation capacity (handling capacity HC) can thus be achieved, and a multiplicity of transportation operations can be carried out in particular simultaneously by the elevator system. Elevator systems of this type are referred to as for example shaft-switching multiple-car systems.
However, elevator systems of this type have the disadvantage that empty cars which are currently not being utilized for a transportation operation can obstruct other cars in elevator shafts. These empty cars thus, where appropriate, have to be moved first in order for other cars to be able to carry out a respective transportation operation. However, moving empty cars and not utilizing them for transportation operations is associated with unnecessary energy costs.
A possibility for depositing empty cars in a depository shaft in an elevator system is described in EP 1 367 018 B1. In the case of a request call, cars which have been deposited in the depository shaft can be provided again. This depository shaft is disposed between two elevator shafts having access openings. The depository shaft does not have any access openings.
A depository shaft of this type is associated with a large space requirement. Furthermore, in most instances, depository shafts of this type cannot be retrofitted in buildings.
EP 1 619 157 A1 discloses a method for operating an elevator system similar to the elevator system as per EP 1 367 018 B1. A special case during the operations process is described herein, in which a car by virtue of a defect unintentionally blocks the elevator shaft. The intact cars are now diverted by way of other elevator shafts.
An elevator system in which the shaft doors are set back from the travel path by at least one car width such that cars can pass another car in front of a door is shown in U.S. Pat. No. 3,658,155. Therefore, transportation operations of other cars do not have to be interrupted when a car stops. However, any storage of cars is not possible since the shaft door would be blocked in this case.
Such elevator systems also have the disadvantage that through continuous operation many empty runs likewise become necessary for specific situations in which transportation operations are to be carried out often between only a few floors.
Thus a need exists for improved elevator systems and improved operation of elevator systems having a plurality of elevator shafts and a plurality of cars which can switch between the elevator shafts to be further improved.